It is known that the incorporation of ketone carbonyl groups into a polymeric backbone can render polymers photodegradable upon exposure to ultraviolet radiation. The keto carbonyl groups can be located in the polymeric backbone chains, or in a side chain adjacent to the main polymeric backbone chain. For example, U.S. Pat. No. 4,042,568 Guillet et al. discloses condensation polymers such as polyamides, polyesters, polyurethanes, polyepoxides, polyamide esters, polyurethanes and polyamino acids, which are photodegradable on exposure to U.V. light, due to the presence in the copolymer backbone of keto carbonyl groups located in side chains adjacent to the main chain of the copolymer backbone, in small amounts.
Condensation polymers such as polyesters have recently assumed an increased measure of commercial importance as disposable containers, e.g. for beverages, where they have received food grade approval for use in containers for soft drinks, beer, etc. As the volume of usage of such polyester containers increases, they become cheap, disposable, throw away items and pose a potential litter and environmental pollution problem. Such problems could be alleviated by making the containers of U.V. photodegradable polymers, so that they would degrade and effectively disappear eventually, if discarded in an outdoor environment where they would encounter incident direct and indirect sunlight. This would be particularly beneficial in remote rural areas, where collection of litter is uneconomic. Materials such as those described and exemplified in U.S. Pat. No. 4,042,568 are satisfactorily U.V. degradable, and fulfill most of the requirements in this regard. They are, however, relatively expensive, since they are prepared by polymerization of special keto-containing condensable monomers. If photodegradable condensation polymers are to complete successfully with regular condensation polymers in high volume, disposable food and beverage packaging applications, they must be price competitive therewith.